The present invention relates to a cutinase variant, more particularly to a cutinase variant having improved thermostability. The invention also relates to a DNA sequence encoding the variant, a vector comprising the DNA sequence, a transformed host cell harboring the DNA sequence or the vector, to a method of producing the variant, and to use of the variant.
Cutinases are lipolytic enzymes capable of hydrolyzing the substrate cutin. Cutinases are known from various fungi (P. E. Kolattukudy in xe2x80x9cLipasesxe2x80x9d, Ed. B. Borgstrxc3x6m and H. L. Brockman, Elsevier 1984, 471-504). The amino acid sequence and the crystal structure of a cutinase of Fusarium solani pisi have been described (S. Longhi et al., Journal of Molecular Biology, 268 (4), 779-799 (1997)). The amino acid sequence of a cutinase from Humicola insolens has also been published (U.S. Pat. No. 5,827,719).
A number of variants of the cutinase of Fusarium solani pisi have been published WO 94/14963; WO 94/14964; Appl. Environm. Microbiol. 64, 2794-2799, 1998; Proteins: Structure, Function and Genetics 26, 442-458, 1996; J. of Computational Chemistry 17, 1783-1803, 1996; Protein Engineering 6, 157-165, 1993; Proteins: Structure, Function, and Genetics 33, 253-264, 1998; J. of Biotechnology 66, 11-26, 1998; Biochemistry 35, 398-410, 1996.
Fungal cutinases may be used in the enzymatic hydrolysis of cyclic oligomers of poly(ethylene terephthalate), e.g. in the finishing of yarn or fabric from poly(ethylene terephthalate) fibers (WO 97/27237). However, it is desirable to improve the thermostability of known fungal cutinases to allow a higher process temperature.
The inventors have found certain variants of fungal cutinases having improved thermostability.
Accordingly, the invention provides a variant of a parent fungal cutinase comprising substitution of one or, more amino acid residues which is located:
a) within 17 xc3x85 from the location of the N-terminal amino acid (as calculated from amino acid residues in a crystal structure), and/or
b) within 20 positions from the N-terminal amino acid.
The invention also provides a DNA sequence encoding the variant, an expression vector comprising the DNA sequence, a transformed host cell harboring the DNA sequence or the expression vector, a method of producing the variant, processes using the variant and a detergent composition comprising the variant.